screenshot-sequence: no pack reload or loading screen during a sequence

A Horizon pack's hot reload could rebuild the pack under the same name
mid-sequence, unseen by the scene check: it now waits for the reply. A
sequence doesn't start, or ends, while the level-loading screen shows,
which a new world keeps a moment after it is ready. The 30 s limit is on
the frames before the last: the last frame's PNG waits as screenshot does.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

crates/horizon-client-render/src/gfx.rs

@@ -6511,7 +6511,8 @@ impl Renderer {
     }
     /// `screenshot-sequence`: waits (30 seconds at most) for the frame just drawn to finish on
     /// the GPU, and takes the centre depth a `shaders/` pack copied in it, which its next frame
-    /// reads: that frame's, or an error, never an older one.
+    /// reads: that frame's, or an error, never an older one. The last frame's PNG has already
+    /// waited for it, without a limit, as `screenshot` does.
     pub fn finish_sequence_frame(&mut self) -> Result<()> {
         self.device
             .poll(wgpu::PollType::Wait {

crates/horizon-client/src/game/native_shaders.rs

@@ -40,6 +40,10 @@ impl NativeShaders {
 impl Game<'_> {
     /// Builds the pack at `path` when its files changed since it was last read.
     pub(super) fn tick_native_shader_pack(&mut self, path: &Path) {
+        // A reload would replace the pack a `screenshot-sequence` draws: it waits for the reply.
+        if self.screenshot_sequence.is_some() {
+            return;
+        }
         let now = Instant::now();
         let state = &mut self.native_shaders;
         if state.looked.is_some_and(|t| now - t < LOOK_EVERY) {

crates/horizon-client/src/game/screenshot_sequence.rs

@@ -67,6 +67,10 @@ impl Game<'_> {
             || self.pending_entry.is_some()
             || self.pack_reload.is_some()
             || self.pending_save.is_some()
+            || self
+                .remote
+                .as_ref()
+                .is_some_and(|r| r.level_load.is_active())
             || self.flight.is_some()
             || self.world.chunks.is_empty()
             || self.streaming.pending() != 0